Giving up Jailbreak???

Been having some constant issues with phone receiving and placing calls. Thinking about
giving up the jailbreak after 18mths of fun.
One question I have 2g 8gig iphone running 3.0.1 ...How can I loose jailbreak (go back to boring phone) and keep 3.0.1...? I dont want to upgrade to the latest apple update.

A simple restore will do it. when it asks if you would like to upgrade to the latest firmware, just select no. I recently had the same problem, after a period of time of my phone being on (not powered completely off), it will get a call from someone, not play the ringtone and when i pick it up, it's dead, no voice going through. I hang up and call back, no better. They will call back again and still. Only solution was to repspring and it'll work for a few hours and then go back to the same problem. It only happened after I installed a couple of things, mainly changing to this new theme I've been playing around with, decided maybe that was it, removed it and uninstalled other stuff I had on Cydia which made the theme work like Categories, iBlank, iBlank Null, etc. After that, my phone worked again (call function wise).

exactly the problem i was having. thanks for the info, maybe I will do the same...I really like having the JB, and the few things that I run, Backgrounder, themes i created...just frustrating sometimes.